The power maybe the same, but it has been proven that the 6V-92TA will get better fuel mileage. But-in this case since the 8V-71T has a manual and the 6V-92TA has the V730, the fuel mileage may nod to the 8V-71T. Even though I have an 8V-71 turbo in my bus, I would get the bus with the 6V92TA and the V730.

As I've told some of my trucking friends, I've driven just about every type of truck transmission- 5spd, 6spd, 5spd with 2spd rear axle, 5x4 twin stick, 7spd, 8spd, 9spd, 10spd (both regular and Super 10), 11spd, 13spd, 15spd, 18spd, 10spd Autoshift, 10spd Ultrashift, 11spd Ultrashift Plus, 12spd Mercedes auto, 12spd ZF auto. But there is only one transmission that always brings a smile to my face, and that is an Allison automatic. Nothing performs off the line (except for another torque converter automatic-like a ZF or Voith) like a torque converter automatic. Now when Allison finally releases the new TC10 10spd twin countershaft transmission with torque converter and continuous power-that will be a winner! Get the economy of the twin countershaft transmission with the performance of the torque converter continuous power shift transmission. Good Luck, TomC

I have favoured the V6 over the years for good mileage,,but they are sensitive to overheating,, if the cooling system is up to par then its a no brainer.>>>Dan

Actually, the 8V71T is notorious for overheating and cracking heads. The 8V71TA with updated heads is a better choice, but it still gets less fuel milage than the 6V92TA. The Silver 6V92TA with by-pass blower and MUI at 350 is bullet proof if mantained with an adequate sized radiator. The 350HP does not overstress the 6V92TA in any way. I'm very happy with my 92 and never hurt it in those few instances where I didn't reach for the radiator water sprayer early enough when going uphill while towing and the engine safety shut-down did what its supposed to do.

Merely the choice between a standard and auto transmission would make it an easy decision for me. We change out the Spicer for an Allison and, expensive as it was, I feel it paying me back every time I sit in the driver's seat. If you buy the standard, there will definitely be many times that you will think to yourself that you made a mistake. You will never b e driving an Allison and wishing you had bought the Spicer though.

As far as the engines go, they are both good. There are many with preferences for one over the other, but no one could call either on a sub standard engine. One possible disadvantage of the 8V71T in this case, would be the question of whether everything was upgraded to turbo spec parts. I suppose the receipts may be able to tell you that.

Like Geoff said the 350 hp 8V71T was not that great it smoked and heated like crazy with the N75 injectors, the 370hp 8v71TA was a good engine it used modern injectors ,different blower, different heads,valves and water passage

While nothing sounds better than a good 2-stroke Detroit, some Detroits just sound better than others. A V8 Detroit just SOUNDS soos much better than the six. Kinda like the difference between some foreign mill and an American V8. I'm also wondering how they cool that 3 speed automatic? Damm that clutch wear...full double clutching ahead! HB of CJ (old coot) (who loves to shift for himself)

8v71t 968 ft/lbs @ 1400 RPM vs 6v92ta 1020 ft/lbs @ 1200. the 52 ft/lbs won't make a lot of difference but that 200 RPM difference in peak torque will make the 6V92 feel like it has a bunch more power and should be good for a mile or 2 to the gallon if driven with mileage in mind. Gear it to cruise at 65 mph @ 1600-1700. Neither one of those transmissions will do you any fuel mileage favors but there aren't a lot of options there. Does that 730 at least have a lock up converter?

The 8v71 if tuned properly will have that unmistakable eat nails and $h!t barbed wire snarl that the V6 can't quite pull off.

My first new truck was an 87 Freightliner with a 3406 that wouldn't get out of its own way. I took it back to Cat and they said they wouldn't even look at it until it had 100,000 miles on it. I told them it would have a Silver engine with 2 valve covers on it long before that. At least it would sound like it was trying lol.

Since it started to drift anyway I try to discourage people souping up the 8v71 it makes no sense to me you take a 8v92TA set it at 350 to 400 hp it will out preform and get better fuel mileage than the 8v71 or 6v92, the 92 series don't mind 2200 rpm all day the 2500 rpm they don't care for that much